The Stovebolt Site Forums The Parking Lot Big Bolts help identifying components

Bare with me while I explain what ive got and what im looking at. Hello ive got a 59 gmc 350 2 ton truck that has a vac booster brake system. I might be calling that the wrong. Its the factory brake system with what looks like an air tank mounted on the frame. My truck also had a pto hydro pump and hydro cylinder but that stuff has been removed. Also I think the master cylinder has been upgraded to a dual chamber. SO my question is what are these pipes coming from my firewall. None of which are going anywhere. They are not connected to anything. I want to pull them off and trash them but I just want to make sure that there not anything that needs to be hooked back up. Here are some links to photos identifying these pipes.

Pic 1

The pipes with the green circles go to what looks like a valve mounted on my sm420 trans. This valve has two outlets on it that dont go anywhere. There is also a 1/4 steel cable on this valve that also goes to nothing. I dont know that this is a valve...I really have no idea what it is. (Identified in next pic) The pipe with the square doesnt go anywhere, both ends are open. And when I say "doesnt go anywhere" I mean the ends are open or there is nothing connected to it.

[IMG]http://i1380.photobucket.com/a...22a215134_zpsmnk46omd.jpg~original[/IMG]

Pic 2.3
This is the valve mentioned above. The valve is the red dot. The two oulets that I mentioned you cant see as the thing with the blue dot is blocking them.

[IMG]http://i1380.photobucket.com/a...b54236f5d_zpsehvo0xnf.jpg~original[/IMG]

[IMG]http://i1380.photobucket.com/a...cf696c077_zpsvo9ekleq.jpg~original[/IMG]

Pic 4,5
Here is my master cylinder and what looks like a modern type booster. Is this a stock setup??? My truck still has the original tank like booster. (no pic)

[IMG]http://i1380.photobucket.com/a...22_152535_zpsdqsp3hil.jpg~original[/IMG]

[IMG]http://i1380.photobucket.com/a...22_152621_zpsxzhedr99.jpg~original[/IMG]

I forgot to mention that in reference to pic 1 there is nothing on the otherside of the firewall. With the exception of the pipe with the green circle on the far left. It looks as though it comes out just under the steering column but is nothing more than a black canister. Maybe somekind of filter.

bcgmc,

The valve on the transmission was the vacuum 2-speed rear control valve. The valve had a push/pull cable that went up to the gear shift knob for high/low selection. The vacuum lines attached to the valve went to the rear (Hi & Lo), vacuum supply up to the fire wall and a small line up to the speedometer adaptor. Do you still have a 2-speed rear?

The steel vacuum lines on the fire wall looks like it could be the fresh air filter for the Hydrovac. Is it attached to what looks like a valve cover breather cap mounted inside the cab?

The other lines on the fire wall are the vacuum lines, check valves to prevent backfires from blowing the vacuum lines up etc. You could have a large vacuum tank mounted on the frame as well.

The large cannister on the frame is most likely the original Hydrovac (brake booster) that was abandoned when they install the modern dual pot MC with it's booster attached.

Hope this helps,

Mike B

Yes I do but it has an electric hi\low shift motor. Can I take this valve off, is there any gasket from the valve to the transmission or is it just mounted there?

Yes there is a roughly 6" round canister mounted under the dash. It goes to the far pipe on the left on the firewall.

Yes I have a big tank mounted on the frame. About the size of a 5 gallon bucket.


Ok you say "abandoned" so I can remove all of this stuff including the original hydrovac tank? From looking at the pics of my MC can you confirm that it is a dual pot MC and that is a modern brake booster? Did the factory MC not have any type booster mounted directly to it? In other words the MC mounted directly to the frame?

Thanks Mike. Yes big help...

Your rear has been swapped to an Eaton with electric shift. More than likely it also has a higher GVW rating then the Corporate vacuum 2-speed that came in your truck. How fast is your truck, it may have good road gears and could run 65 mph or more...

Most vacuum tanks I've seen are about 8-10" diameter and about 24" long and are mounted under the step on the passenger side.

If you no longer have anything that is vacuum driven than all of that abandoned piping can be removed.

The 2-speed valve is mounted to an ell bracket with two bolts, remove and replace the bolts and you're done.

The original Hydrovac (brake booster) was mounted separate from the MC. Yes you have a dual pot MC as seen by the two lines coming out of the side of the MC. I don't know the vintage, but it's newer than the truck...

Mike B

I havent been able to drive it. I bought it with a non fuctional rearend. The sun gear in the rearend is in pieces. I have to repair the rearend or replace it.

My vacum tank is about the size you describe however it is on the drivers side. I dont know if its still in use or not.

I'd guess it's been abandoned as well (all of the lines on the fire wall have been disconnected). What devices on your truck need vacuum...wipers?

Mike B

Thanks for the help Mike. I got under the truck again and checked all the line from the hyrovac. There is nothing connected to it but one line that runs up to the DS fender with what looks like a filter. Whoever did the dual MC and booster still have the rear brake line coming from the MC to the hydro booster and then to the rear brakes. I think they only did this so they wouldnt have to mess with redoing the rear brake lines.

You do have an item using vacuum, the new brake booster...I conpletely overlooked that. You may want to keep the tank as back-up if the engine quites while driving you'll have some reserve.

That filter looking thing is most likely the fresh air filter that's piped (looks like a 3/4" heater hose) to the back canister of the Hydrovac.

Mike B

But where is the tank getting vacum from? It has no lines to it other than the filter on the fender. Also there is a small electric vacum pump on the frame that goes to the new booster. And it also get vacum from the intake. But nothing to the hydrovac.

OK, so the vacuum is taken care of by the electric pump, that's why they abandoned the big tank.

The Hydrovac is also abandoned. It would have had a fresh air line on the back if the cannister and a vacuum line attached to the control valve on the hydraulic side. When the hydraulic brake line at the Hydrovac sees pressure (you stepped on the brakes) the vacuum valve opens and the air is sucked out of the one side of the cannister and fresh air at 14 psi on the other side pushes the piston (in the middle of the cannister) into the Hydrovac's MC applying more pressure in the brake lines...vacuum assist! Sorry for the loooong sentence...LOL.

Mike B